Pretty sure it was this one linked in the OP. See this footnote: https://mcfunley.com/choose-boring-technology#f4

> A good example of this from my experience is Etsy’s activity feeds. When we built this feature, we were working pretty hard to consolidate most of Etsy onto PHP, MySQL, Memcached, and Gearman (a PHP job server). It was much more complicated to implement the feature on that stack than it might have been with something like Redis (or maybe not). But it is absolutely possible to build activity feeds on that stack.

> An amazing thing happened with that project: our attention turned elsewhere for several years. During that time, activity feeds scaled up 20x while nobody was watching it at all. We made no changes whatsoever specifically targeted at activity feeds, but everything worked out fine as usage exploded because we were using a shared platform. This is the long-term benefit of restraint in technology choices in a nutshell.